Transformers are used to increase or decrease the voltages of alternating current in electric power applications and are typically mounted either above ground on a junction pole, or at ground level on a pad commonly formed of concrete. In pad-mounted transformer applications, an end of an underground cable is routed from the ground up through an opening in the pad for connection to the transformer via a terminal. Because pad-mounted transformers are located at ground level, they present a risk to anyone who may come into contact with them. More specifically, there exists a significant risk of serious injury or death to anyone who comes into contact with the high voltage connections between the underground cable and the transformer. The increase in use of underground power distribution systems has resulted in a corresponding increase in the number of pad-mounted transformers, and thus a corresponding increase in risk. In order to minimize this risk, pad-mounted transformers are typically enclosed in a metal cabinet, also referred to as a transformer “box,” to prevent tampering with the dangerous electrical connections inside. Authorized technicians who service the transformers may gain access to the electrical connections and transformer components generally by opening a large access door located at the front of the cabinet and which is otherwise maintained in a closed and locked condition.
When an underground power cable faults resulting in loss of power, in order to restore power as soon as possible, many power companies will connect a temporary emergency cable, also called a “ground strap”, above the ground between a transformer and the building needing power (or between two transformers) until the faulted line can be repaired. Surprisingly, many existing transformer boxes do not provide an above ground entry point, called a “mouse hole” or “rat hole”, through which a temporary repair cable can be threaded. It is unsafe to run the temporary cable through the cabinet door because such a practice would leave the dangerous electrical connections accessible to the public. Moreover, cutting a hole in the cabinet or cabinet door is not a recommended practice for safety issues and because upon removal of the temporary cable the opening would have to be repaired resulting in additional labor, time and expense. Accordingly, in order to connect the ground strap to the transformer, the current practice is to create a temporary subterranean entry point for the cable by digging a hole next to the transformer, tunneling under the transformer pad, and then up to the pad opening so that the ground strap may then be threaded through the tunnel and into the cabinet. This is a time and labor intensive task, particularly when performed when visibility is low such as at night, in inclement weather such as during extreme heat, cold, rain or snow, and/or when ground conditions are poor such as when the ground is frozen and/or comprised of rock or stone.
Given the considerable number of pad-mounted transformers that do not include a secure entry point for an emergency repair cable, and given further the significant cost in time and labor associated with creating a subterranean cable access point, it is clear that there exists a need in the art for a safe and cost effective alternative means for providing secure temporary cable access.